1. Field of the Invention
The present invention relates to a vibration type actuator driving control device and, more particularly, to a driving control device for a vibration type actuator for obtaining a driving force by exciting a vibration member by applying an AC signal to electromechanical energy conversion element.
2. Related Background Art
Conventionally, in speed control on a vibration type actuator, the actual speed of the vibration type actuator is detected, and the speed of the actuator is brought close to a target value by feeding back the detected value.
Vibration type actuators vary in characteristics and are required to reduce the influences of such variations. For this reason, the characteristics of each vibration type actuator must be measured in advance, and an optimal control state must be ensured by setting a control gain in accordance with the characteristics.
In addition, the characteristics of a vibration type actuator vary with changes in ambient temperature. In the driving control device for the ultrasonic motor, for example, disclosed in Japanese Patent Application Laid-Open No. 4-210787, therefore, a temperature sensor is arranged to set a control gain in accordance with temperature information from the sensor.
According to one aspect of the application, it is an object to optimize a control gain for a vibration type actuator.
According to one aspect of the application, there is provided a control device for a vibration type actuator for obtaining a driving force by exciting a vibration member by applying an AC signal to an electro-mechanical energy conversion element, comprising, as a gain setting arrangement, an operation control circuit which determines the AC signal with respect to an input control signal, in accordance with a control gain, and controls an operation of the vibration type actuator, a speed commanding circuit which commands a change of an operation speed of the actuator, a changing circuit which changes a value of the control signal in accordance with the changing command for the operation speed, and a gain determining circuit which determines the control gain on the basis of a relationship between a change amount of the value of the control signal and a change amount of speed.
Other features and advantages of the present invention will be apparent from the following detailed description in conjunction with the accompanying drawings.